<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Promise</title>
  </head>
  <body>
    <script>
      function cbFun() {
        console.log("hello word!");
      }
      function asyncFun(callback) {
        return new Promise((resolve, reject) => {
          setTimeout(() => {
            resolve();
          }, 3000);
        });
      }
      asyncFun().then(()=>{
        cbFun()
      })
    </script>
  </body>
</html>
